It depends on the will or trust you are administering, but most wills and trusts direct that equal distributions be made "after" paying all expenses of administering the estate and distributing the assets. That means the net of all appraisal, selling, and administrative expenses are shared equally by all parties, irrespective of the form of the assets they ultimately receive.

If you want to deviate from that approach, you need to get 100% of the heirs to sign off on it, but it sounds like everyone is not going to agree. You probably need an attorney so you can simply say that your legal counsel advised you that expenses of the estate, including any expenses for selling and distributing property, have to be shared equally among all heirs. If the heirs that want property cause problems and refuse this approach, then you tell them their options are either equal sharing of expenses or else you have to sell everything and distribute only cash (again, just following legal counsel).

You can acknowledge the alternative approach is logical and would be perfectly fair, but that you cannot change the direction provided in the will.